Portland cement has long been a standard building material. Over the years, various modifiers have been developed for Portland cement formulations to provide particular properties or advantages, such as more rapid curing, compatibility with and resistance to certain materials, varying strengths, etc. Frequently, the modified formulations have worked at cross purposes, so that a Portland cement formulation which initially cures more rapidly results in a final product with a lower strength, while the higher strength Portland cement formulations frequently cannot be demolded for substantial periods of time because there is not sufficient early strength.
In the past few years, geopolymers have been found which, though mineral in composition, provide many of the properties of molding resins, such as epoxies and polyurethanes. Such geopolymers are described and claimed, for example, in U.S. Pat. Nos. 4,349,386 and 4,472,199,each in the name of Joseph Davidovits. These geopolymers are primarily composed of silicas and aluminas, mixed and reacted in particular ways to provide the desired structure. While, in general, these geopolymers are perfectly adequate for the purposes intended, as such, they do not provide the types of strengths sought in a Portland cement composition.
The art has continued to seek a Portland cement composition which provides for utilization in standard situations, while providing both a high early strength and an ultimate, very high strength. In particular, compositions having a minimum strength of 4,000 psi at 4 hours, the release strength necessary for prestress work, have been sought.